The present invention relates to a method of manufacturing a photomask and a technique for manufacturing a semiconductor integrated circuit device. Particularly, the present invention relates to a technique effectively applicable to a photolithography (hereinafter, referred to as lithography) technique, in which a predetermined pattern is transferred onto a semiconductor wafer (hereinafter, referred to as a wafer) by the exposure using a photomask (hereinafter, referred to as a mask) in a manufacturing process of a semiconductor integrated circuit device.
With the increasing demand for further scaling down of dimensions and the integration of patterns such as an element and circuit wiring, the increase in the mask cost has become a problem. This is caused by the various factors as follows: since the scaling down of dimensions and the high accuracy are required also in mask patterns even under the circumstance where the market size of the mask manufacturing field is small and the mask manufacturing is not commercially viable, a costly pattern writing apparatus and an inspection apparatus are required and the equipment cost and the running cost thereof become enormous; it becomes necessary to introduce novel technologies such as a phase shift technology and an optical proximity correction technology; and the defect rate of the mask is increased due to the scaling down of the pattern. With the improvement in the performance of the semiconductor integrated circuit device, the total number of masks required to manufacture one semiconductor integrated circuit device tends to increase. This tendency also causes an important problem to be solved, that is, how to reduce the mask cost.
Techniques for solving such problems are disclosed in, for example, pp. 145 and 146 of xe2x80x9cNikkei Micro Device, April-2000 issuexe2x80x9d issued on Apr. 1, 2000, by the Nikkei Business Publications, Inc., pp. 142 to 152 of xe2x80x9cNikkei Micro Device, May-2000 issuexe2x80x9d issued on May 1, 2000, by the Nikkei Business Publications, Inc., and Japanese Patent Application Laid-Open No. 2000-17196. In these descriptions, disclosed are techniques in which a mask serving as a master (master mask) having high writing accuracy in dimensions is manufactured, patterns of the master mask are transferred onto a daughter mask using a reduced projection exposure apparatus, and the pattern is transferred onto a wafer using the daughter mask. Specifically, masks (master mask and daughter mask) are manufactured according to the process as follows.
Firstly, a mask substrate for a master mask is prepared. On this mask substrate, for example, a metal film such as chromium and a resist film are deposited in this order from below. Subsequently, after a pattern twenty times as large as the design rule is written on the resist film on the master mask, the lower metal film is patterned by the etching method using a resist pattern formed by the development as an etching mask, and thus the master mask is manufactured. Thereafter, a mask substrate for the daughter mask, which is identical to that for the master mask, is prepared. Subsequently, after the mask pattern of the master mask is written on a resist film of the mask substrate for the daughter mask using the reduced projection exposure apparatus such as an i-beam stepper, the metal film is etched similarly to the case of the master mask, and thus the daughter mask is manufactured. In this technique, the costly electron beam writing system is not required. Therefore, the reduction of the mask cost can be promoted.
However, the inventors of the present invention found out that the manufacturing technique of the mask (master mask and daughter mask) described above had a problem as follows.
Specifically, in the case where patterns are transferred onto one daughter mask using a plurality of master masks, it is very difficult to connect the patterns transferred using the plurality of master masks to each other.
An object of the present invention is to provide a technique capable of connecting the patterns transferred using the master masks to each other.
Another object of the present invention is to provide a technique capable of improving the reliability of the connection between the patterns transferred using the master masks.
Still another object of the present invention is to provide a technique capable of improving the reliability of a semiconductor integrated circuit device.
Still another object of the present invention is to provide a technique capable of improving the defect rate of a semiconductor integrated circuit device.
Other objects and novel characteristics of the present invention will be apparent according to the description and the accompanying drawings of this specification.
The outline of the typical one of the inventions disclosed in this application will be described as follows.
Specifically, the present invention includes the steps of: transferring a first pattern onto a photosensitive organic film of a second mask by the reduced projection exposure using a first mask; and transferring a second pattern by the exposure using an energy beam onto the photosensitive organic film of the second mask between the regions transferred using the first mask.
Also, the present invention includes the steps of: transferring a first pattern onto a photosensitive first organic film of a second mask by the reduced projection exposure using a first mask; performing the development to the photosensitive first organic film, thereby forming the first pattern made of the first organic film, then patterning a lower metal film using the first pattern as an etching mask; depositing a photosensitive second organic film on a mask substrate of the second mask; transferring a second pattern by the exposure using an energy beam onto the photosensitive second organic film of the second mask between the regions transferred using the first mask; and performing the development to the second organic film, thereby forming the second pattern made of the second organic film.
Also, the present invention includes the steps of: transferring a first pattern onto a photosensitive organic film of a second mask by the reduced projection exposure using a first mask; transferring a second pattern by the exposure using an energy beam onto the photosensitive organic film of the second mask between the regions transferred using the first mask; and performing the development to the photosensitive organic film, thereby forming the first and second patterns, then patterning a lower metal film using the first and second patterns as etching masks.
Also, the present invention includes:
(a) a step of preparing a set of first masks;
(b) a step of preparing one mask substrate of a second mask;
(c) a step of depositing a photosensitive organic film on the one mask substrate of the second mask;
(d) a first exposure step in which each pattern in integrated circuit patterns of the plurality of first masks is transferred onto a photosensitive organic film on the one mask substrate of the second mask by the reduced projection exposure, whereby a plurality of first regions corresponding to each of the integrated circuit pattern regions of the plurality of first masks are arranged in an integrated circuit pattern region of the one mask substrate of the second mask while interposing second regions between the adjacent first regions;
(e) a second exposure step in which an energy beam is selectively irradiated onto the photosensitive organic film in the second region of the second mask, thereby writing a predetermined pattern on the photosensitive organic film; and
(f) a step of performing the development to the photosensitive organic film, thereby forming a pattern made of the photosensitive organic film on the second mask.
Also, the present invention includes the step of: transferring a pattern onto a wafer by the reduced projection exposure using the second mask.
Also, the present invention includes the step of: processing a lower film of a mask using the pattern as a mask, which is transferred onto the wafer by the reduced projection exposure using the second mask.
Also, the present invention includes the step of: introducing predetermined impurities into the wafer using the pattern as a mask, which is transferred onto the wafer by reduced projection exposure using the second mask.